The present invention relates to a method for preparing a sample for a transmission electron microscope employing a focused ion beam apparatus.
Transmission electron microscope sample preparation methods employing a focused ion beam apparatus are capable of making specified locations of thin-film thinner, and the number of opportunities to use these methods have increased in recent years. In this procedure, a substantial amount of processing is practically impossible using only a focused ion beam. Typically, a large section including an observed location is cut-out from a sample in advance using a machining blade, and is then processed to a thickness of a few tens of micrometers. Thin-film processing is then carried out to reduce the sample to a thin-film of a thickness in the region of 0.1 xcexcm using a focused ion beam.
However, portions of the film at locations other than the location being processed become separated (referred to as xe2x80x9cchippingxe2x80x9d) as a result of a load due to the machining blade when processing employing the aforementioned machining blade is applied to samples containing thin-films. In the worst case, the observation location itself may become chipped, i.e. the film to be observed using a Transmission Electronic Microscope (TEM) may become chipped. Further, because water is employed when cutting with a machining blade, a machining blade cannot be used for cutting when water is not desirable at the observed location.
The periphery of an observed location is grooved using a focused ion beam to the same thickness as a film thickness for which film chipping is possible or greater prior to cutting with a machining blade so that the observed location is isolated from the film composing the sample.
If necessary, in addition to this grooving, thin-films for embedding or protective use are deposited on a surface of the floating island-shaped observed location using a focused ion beam apparatus. By using this method, the observed location will not be damaged even if film chipping occurs. The observed location is also not influenced by water used during cutting with the machining blade if a surface protection film is provided.